This invention relates to a rotary cutting deck for a mower. More particularly, this invention relates to a suspension for elevating at least one corner of the cutting deck above the ground, thereby eliminating the need for a wheel to support that corner of the cutting deck.
Mowers are known for mowing large areas of grass, such as those in parks, golf courses, athletic fields, and the like. Many such mowers comprise a self-propelled traction frame that is part of a vehicle on which the operator sits as the mower is operated. At least one cutting deck, and often a plurality of cutting decks, are attached to the traction frame to cut a swath of grass as the traction frame moves forwardly. In a typical configuration, such a mower often has a front cutting deck extending forwardly of the traction frame and two side or wing cutting decks extending laterally from the sides of the traction frame.
The cutting decks are normally equipped with ground engaging wheels to allow the cutting decks to roll over the ground as the traction frame moves forwardly. A lift arm extends between the traction frame of the mower and the cutting deck to allow the cutting deck to be selectively lifted off the ground and placed in a transport position. In the case of the wing decks, the transport position comprises one in which the wing decks are folded up against the sides of the traction frame. When the cutting decks are not so lifted off the ground and placed in their transport position, they roll over the ground and xe2x80x9cfloatxe2x80x9d relative to the traction frame to allow the cutting decks to follow the ground contours.
In some prior art designs, the wing decks on such a mower are supported by a pair of outrigger wheels attached to the wing deck adjacent the outer front and rear corners of the wing deck. The inner front and rear corners of the wing deck carry no wheels at all. Instead, whatever support is provided from The traction frame, such as the lift arm, is used to keep the inner front and rear corners of the wing deck elevated above the ground. U.S. Pat. No. 5,715,667 to Goman et al. shows wing decks of this type, i.e. wing decks supported by only a pair of outrigger wheels on the outer corners of the frame and a support arm extending from the traction frame.
In decks of the type just described, the Applicants have found that using just a single pair of outrigger wheels on the outside of the wing deck presents problems in achieving a consistently good quality of cut. It should be kept in mind that such wing decks often cut over hilly, uneven terrain in which the wing deck rolls about a longitudinal axis through the wing deck. The Applicants have found that when cutting over this type of terrain, the lack of inner support wheels results in a variation in the height of cut over the width of the path being cut by the wing deck. In other words, the grass cut over the inside of the cutting deck might be cut higher or lower than the grass being cut over the outside of the cutting deck where the support wheels provide a more consistent height of cut. Since this variation in the height of cut can often be seen with the naked eye and detracts from the appearance of the cut grass, it is a disadvantage and desirably should be avoided.
Some mowers are known in which the wing deck is supported by wheels adjacent all the corners of the deck. The Applicants have found that this avoids the height of cut variation described above when only a pair of support wheels are used. However, using four support wheels adjacent each corner of the deck has problems of its own.
First, at least some of the support wheels are typically caster wheels, i.e. wheels capable of pivoting about a vertical support axis as they roll over the ground. Because of the varied and uneven terrain over which the mower operates, all of the support wheels, and particularly the caster wheels, wear quickly and must be periodically replaced. This is a disadvantage.
Moreover, it is desirable that a particular mower be as narrow as possible when the mower has the cutting decks placed in their transport position with the wing decks folded up along the sides of the mower. By minimizing the width of the mower in its transport configuration, the mower is more maneuverable and also fits within as tight a space as possible. This requires that the wing decks be close to the traction frame. When caster wheels are used on the inner corners of the wing decks, these caster wheels may be too close to the frame to avoid interfering with the frame. Thus, the wing deck must typically be moved out from the frame a little further than the designer might prefer in order to accommodate the inner caster wheels. Again, this also is a disadvantage.
One aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has at least one rotary cutting element rotating about a substantially vertical axis in a substantially horizontal cutting plane when the cutting deck and rotary cutting element are in operation. The cutting deck when coupled to the mower has two corners that are closest to the mower and two corners that are furthest from the mower. A plurality of spaced support wheels are carried adjacent at least the two corners of the cutting deck that are furthest from the mower. A corner suspension is connected to at least one of the two corners of the deck that are closest to the mower. The corner suspension comprises at least one upwardly biased connecting link attached to the at least one corner of the cutting deck, the bias on the connecting link being sufficient to elevate the at least one corner of the cutting deck above the ground without using a support wheel adjacent the at least one corner.
Another aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has at least one rotary cutting element rotating about a substantially vertical axis in a substantially horizontal cutting plane when the cutting deck and rotary cutting element are in operation. An attachment is provided on the cutting deck for coupling to a pivotal lift arm extending laterally outwardly from one side of the mower. The cutting deck when so coupled to the lift arm has inner front and rear corners that are closest to the mower and outer front and rear corners that are furthest from the mower. Three support wheels are carried adjacent the inner front, the outer front and the outer rear corners of the cutting deck. A corner suspension comprises at least one upwardly biased connecting link attached to the inner rear corner of the cutting deck. The bias on the connecting link is sufficient to elevate the inner rear corner of the cutting deck above the ground without using a support wheel on the inner rear corner.
Yet another aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has four corners. Ground engaging wheels are located adjacent three of the four corners of the deck. A corner suspension is provided for the fourth corner of the deck. The corner suspension includes an upwardly biased connecting link acting between the mower and the fourth corner of the deck. The connecting link is biased to lift upwardly on the fourth corner of the deck with a biasing force sufficiently strong to elevate the fourth corner of the deck above the ground. The corner suspension takes the place of a ground engaging wheel on the fourth corner of the deck.